*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
.container{
    width: 1200px;
    margin: auto;
}
.col{
    width: 33.3333333%;
    float: left;
    height: 100px;
    background: palevioletred;
    font-size: 20px;
    color: purple;
}
.container::after{
    content: "";
    display: table;
    clear: both;
}
@media (max-width: 600px) {
    .container{
        width: 100%;
    }
    .col{
        width: 100%;
    }
}


